Motor with extra cooling of the air or fuel mixture before admission into the working cylinder



Jul 2 1927. 1,636,937

y 6 o. w. HULT MOTOR WITH EXTRA COOLING OF THE AIR 0R FUEL IIIXTURE BEFORE ADMISSION INTO THE WORKING CYLINDER Filed July 25. 1924 Ff; l. v

Patenied July 26, 1927.

UNITED STATES PATENT oFFicE.

osera wALrmn HULT, or sTocxiIoLM, sWnDEN.

MoTon WITH EXTRA oooLING or" THE AIR on FUEL MIxTUnn BEFORE ADMISSION INT THE WORKING CYLINDER.

Application led July 25, 1924, ,Serial No. 728,282, and in Sweden November 28, 1923.

This invention refers to a method ofl Y' bringing about eiiicient cooling of theair or extreme position.

the fuel mixture for internal.A combustion motors, that the air 9i' mixture, as the case may be, after having been compressed and cooled is allowed to re-expand and to exert its pressure upon the compressor piston, during which process it iscooled in order to be introduced into the working cylinder at the next` stroke of the compressor piston.

. On the accompanying Ldrawing' there is shown by i Vway of example a four-stroke motor constructed accordin to this invention. F ig. 1 is a vertical section ofthe motor and shows the com ressor piston in its upper ig. 2"'shows the location of cooling piges in relation to the compressor head, and ig.13 shows a cam for the positive driving 'of the motor valves, this cam acting in both directions. The air or fuel mixture is compressed by a piston a propelled b the engine crank, moving in a cylinder, in which the air or fuel mixture enters through a suction valve 2'.. The upper part of the compression chamber for the air or the motive mixture is formed by pipes lz, which are iixed'in the compressor cylinder head andthe lower ends of which communicate with the chamber in the compressor cylinder, while Ythe upper ends are closed. These pipes are surrounded by the cooling water in a cooling jacket c, which in the example shown surrounds not only the compression cylinder but also the lworking cylinderh of the motor, in which cylinder the motor or working piston 'g moves! It should, however, be

observed that it Tis more suitable that the two cylindershave each ay separate water jacket.' From the chamber in the compres` `sor cylinder there extends a pipe d to acham erv c arranged in the head f the Vworking cylinder h, from which chamber the lair .or mixture flows intothe' working cylinder 'Iz past a spring actuated valve By;

means of another spring actuated va ve the 1 exhaust of the vcombustion products from theworking cylinder la, is regulated. These two valves are driven from the motor shaft by means of a cam k (Fig. 3'). 7

` The motor describedworks' in the followin manner. l

e air or mixture is in the shown, position of the compressor piston a compressed and iills the cooling pipes 5, which are suro5 rounded by the water circulating in the cooling jacket c. At the same time the pipe d and the valve casing e are iilled with compressed air orV mixture, and the spring pressure uponthe valve f isvso greatthat the valve tightens against the pressure ofthe air or the mixture, which pressure may reach 3 to 4 atmospheres or even more.

v The air or mixture, which inthe shown l position of the compressor piston a has been deprived of the vgreater part of its compression heat by .the greater part of its volume Vbeing enclosed in the waterVJ cooled pipes I drives by its pressure the piston a downward, until it has expandeddown to atyy mospheric pressure, thereat being cooled according `to the usual formula for the cooling expansion stroke has reached its lower extreme position,-the motor` liston g, which works on the four stroke principle, has just m completed its ordinary exhaust stroke. The valve f opens, and the piston ,g begins to `move downward', while the compressor piston c simultaneously moves upward, the cooled air then rushing into the working cylinder 71,. S5

At the next downward movement of the `compressor piston a the next charge of air or mixture is being sucked in through the suction valve z", after which a new compression occurs during the cooling of the air by stroke principle: suction, compression, L exf. pansion and exhaust, only with the differv ence that the piston of the working cylinder during the said exhaust serves asa suctlon member, which is an advantage and prevents the'rise of'pressure of thecooled air, where.- f v100 by all unnecessary increase of hea t during the suction stroke in the working cylinder is obviated, vand occurs rst during the com pression ofthe charge in the said cylinder.'

The suction ,valve z' of the air pump or 105 compressor is ablevto`serv'e as a regulator, so

`'that fresh air or mixture flows through thesaine, e. Lg. it the air or mixture, through the different sizes of thepistons, is rarefied to or below atmos heric pressure, e. g. to 0.9 ata `mospheric a solute pressure, in which case presse and cooled quantity of air to expand in the compressor itself, andthere by presV sure upon the compressor piston return the greater part of the work expended in compression, the,l motor obtains an eiect increased to a corresponding degree. i

3. The cooling becomes more efficient, as

` the air is allowed to exert its expansion,` pressure in the strongly cooled'compres'sion cylinder, where re-heating is considerabl less than it can become in the working cy inder heated by explosion.

4. The pressure between the air` and cylindei` walls can be reduced, so that it is" less than atmospheric pressure, after the expansion or cooling stroke is completed, Lge/Wheny the cooled air is introduced. into the working cylinder of the motor, by making thestoke volume of the said c linder greater than the stroke volume of t e compressor cylinder i which causes a corresponding rarefaction of air.

- 5. The device becomes remarkably simple by the ordinary four stroke cycle without any extra member regulating the course of working in the com ressor, disregarding the small suction valve c, which requires no posi-'- tive driving. v

As to the rarefaction of air mentioned in f the precedingclauseAL it `may be observed that in orderV tol enable the same' to take f place-by the stroke volume of the workin cylinder'being inade reater than that o the com ression cylin er, the ,suction valve z' shoul be positively governed in: such a manner that onl that, quantity of air '(or mixture), for w ich there Iis room in) the` compressor, cylinder, is admitted Lint/oy the working cylinder, for otherwise the latter.'

cylinder may during its suction stroke receive air (or mixture) through the suction valve a.

This regulation of the admission of air (or mixture) mayaccording to the preceding description a so be arranged in lsuch a manner` that the degree of charging inthe l working""'cylinder of the motor isd'etermined bythe saine, independent of the greater or less volumenl of the compressor, e. g. in such a manner that the motor when running normally, receives only so much air or mixture asJ finds room in the compressor cylinder, in which case this cylinder receives a 73% charge, which corresponds to the increased condensation of the air or mixture as a con- -f sequence of being cooled to 0 C. at the beginning of the compression in the working cylinder, or in such a-manner that the positively governed suction valve-z' or, if desired, an extra suction valve (or both), if a greater degree ofcharging or a complete charge is wished, allowsJ the entrance of air or mixture e. g. durin the Whole suction stroke of the working piston, if, in case of need, an increase of the volumetric effect of the motor beyond the ordinary is wished.

" As will be seen from the process described,

' the intended method of working should with absolute certainty be obtained to such `a high degree that the-temperature of 0 C. or below can befreached before the commencement i of compression in the working cylinder of `the motor,',without any `increased loss of power needing to arise through a high compression in the compressor or air pump. c

The motor can also be cbnstructed in any other manner than the o'ne stated with regard to various requirements, e. g. ywhen the greatest ossibleamount of power with somewhat re uced economy is preferred, the

`stroke volume of the compressor may be equally great as or even greater than the f stroke volume of, the Working cylinder, by which means a heavier orma ater quantit of air is admitted into t emotor, besi es what will be gained through the condensation caused by the cooling.

'Ifhe compressor may be provided witlr two.l

or more pistons; located inY a corresponding number of cylinders, or it may be doubleacting, e. g1 in a two stroke motor or ina ies two cylinderfour stroke motor with a com-l presser common to thecylinders. Even the cooling device may bearranged in any other manner than that stated, e. g.

the air or mixture may during the compression be made to circulate, through tubes cooled in some suitablev manner, by which means the coolingy can be brought about in lll) ashorter time, if desired, e. g., in the case of vey high speed motors. t. avingnow described I cla-im as new and desire tol secure by, Let-v ters Patent is:

1. The method of effecting `a. double cooling of a gaseous mixtureto be used in an `internal combustionengine, consisting in first compressing said mixture and simultaneouslyl subjecting the same t0 a cooling ac? tion, t

my invention, what en allowing thev mixture to expand l during further cooling, and4v finally introl ducin the mixture into the engine.

methodasigclaimed in laim 1, -includingthe step .of the4 'expansion of the charge to impart an impulse to the engine. y

3. An" internal combustion engine including in combination av jacketed compression cylinder, a jacketed 'working cylinder, in communication therewith, pistons operating in said cylinders, a main shaft to which, both Y of said pistons are connected, intake valves -for both ofI said cylinders, a cooling device in the jacketed head of the compression cylinder, and means for controlling the operation of the intake valve of the working cylinder in timed relation with the operation of the intake valve of the compression cyl.- v

inder.

4. An arrangement as claimed 1n claim 3, wherein an exhaust valve is provided for` the working cylinder, and operated by the means which operates vthe intake valve for the said cylinder and in timed relation with respect tothe operation of thesaid intake valve. p

5. An arrangement as claimed in claim 3, wherein the piston of the compression cylinder is of less dis lacement than the piston of the woring cy inder and wherei`I said pistons are connected in opposed relation. to the shaft and o erate` on thel I:four stroke cycle, substantial y as-and for the purposes set forth.

In witness whereof I have hereunto set my hand. v

OSCAR WALFRID HULT. 

